We had (have?) a virus on our desktop computer. My husband had one of his friends run a system restore on the computer because he didn't want to wait for me to fix it. I'm not sure if this is all the friend did or not, I wasn't there. Now, all that comes up after startup is a blank white screen. I'm pretty sure all of my regular programs are running in the background (for example, it will chirp "avast virus database has been updated") but I cannot access them. Any ideas?